Mobile communications systems are known which can provide enough bandwidth to allow streaming of video using advanced compression techniques, such as MPEG-4. For example, a third generation mobile network has a maximum bandwidth of 384 kilobits per second (kps). However, this is not enough for some types of services, such as file downloading.
Nevertheless, higher bandwidth transmission systems are known. For example, a Digital Video Broadcasting (DVB) transmission system can provide bandwidth of 10 Mbps or more. Thus, it is possible to augment a mobile communications system with a higher bandwidth transmission system.
DVB receivers are known in applications such as digital television. Usually, DVB receivers are fixed and mains-powered. However, mobile handheld terminals are usually battery-powered and so power is limited.
The average power consumption of a DVB receiver can be reduced by using a scheme based on time division multiplexing (TDM). Such a scheme is called time slicing.
If a service is requested, data can be transmitted using time slicing. Bursts of data are sent using significantly higher bandwidth compared to the bandwidth needed to send the data using static bandwidth. Each burst includes an indication of time to the beginning of the next burst, which is referred to as “delta-t”. Between bursts, data is not transmitted, allowing other services to use the bandwidth allocated to the service. Thus, the receiver need only stay active for a portion of time while receiving bursts. Nevertheless, received bursts can be buffered and consumed at a relatively more uniform and lower rate.
At present, time slicing cannot be used for some types of data. This is because data structures, such as Entitlement Management Message (EMM) sections which are used to transmit the EMM messages, cannot accommodate time slicing information, such as delta-t.
The present invention seeks to ameliorate this drawback.